Process for dewaxing oil



Patented Feb. 8, 1938 I 2,101,772 PATENT, Y OFFICE rnoon ss FOR nnwaxmo on.

Maner L. Wade, Long Beach, Calif., assignor to Union Oil Company or California, Los Angeles, Calif., a corporation of California No Drawing.

8 Claims.

This invention relates to the electrical separation of wax fromwax-bearing oil and particularly to aids and accelerators to dewaxing waxbearing oil by electrodeposition or electroplating. In the processes for dewaxing oil electrically the wax-bearing oil is mixed with a suitable diluent, chilled to a temperature at which wax is precipitated out of solutionas a finely divided wax suspension and the wax suspension removed from the mixture by electrodeposition upon electrically charged electrodes. In most cases the wax precipitates formed in unrefined oils are comprised of negatively charged wax crystals or particles and are deposited or plated in a solid cake or layer upon the positive electrode under the influence of an electric field.

Objects of this invention are, to increase the rate and efliciency of dewaxing wax-bearing oil by electrodeposition methods.

It has been found that the rate of electrodeposition can be increased by the addition to the oil or oil diluent mixture prior to chilling and electrical treatment certain extraneous substances which act as promoters or accelerators.

It is believed that these substances, upon chilling, may be co-precipitated with the wax to be removed from the oil, and that the'effect of the co-precipitated substance upon the wax is favorable to electrodeposition.

For example, a number of dewaxlng tests were run on Santa Fe Springsraw lubricating oil dis ing oil distillate wasfirst diluted with 50 volume Application September 22, 1934, Serial No. 745,167

percent of light hydrocarbon distillate having a. boiling point range of approximately 326 to 395 -lit, then a small quantity of an accelerator was added to the oil diluent solution and the mixture chilled to a temperature at which wax precipitated from solution in the form of a fine suspension.- This mixture was subsequently subjected to a unidirectional electric field between oppositely charged, fiat plate, immersed electrodes having areas of 8 square inches and spaced inch apart from face to face. Under the influence of the unidirectional electric field the precipitated wax was removed from the waxbearing mixture as a deposit or plated layer upon the positive electrode. Blank tests were simultaneously made in the same manner and under identical conditions but without the accelerators being added, in order to determine the relative rates of electrodeposition with and without the said accelerator. tions of the hereinbefore described tests.

It was discovered that the accelerators when added to the waxy oil solution at'temperatures at or below the cloud point of the solution, were ineffective to increase the rate of wax deposition while those same accelerators when added at a temperature above the cloud point were effective in increasing the rate of electrodeposition. The electrodeposition accelerators listed hereinafter in Table I were therefore added to the waxy oildiluent solutions attemperatures of 120 F., or higher, which were temperatures well above the cloud point of the oil solutions.

Test

Deposit Voltage between electrodes Electrodeposition Tem accelerator Grams increase b b- H l- OOOOFOQIQQOI assesses-ea Table I indicates the condi- Additional substances not included in Table I which were found to act as accelerators to electrodeposition of wax by the same test methods are as follows: acetic acid, alpha bromonaphthalene, p-dichlordiphenyl,.palmitic acid, naphthalene, pyrogallol, oleic acid, cresol, trioxymethylene, p-aminophenol, pyridine, albino asphalt, nitrobenzene, sodium phenoxide, benzoic' acid, aniline and calcium naphthena't'e.

It is not known certainly what the chemical compositions of the waxes are, but they are believed to contain montanic, melissic, carnaubic, cerotic and other fatty acids ofthe general formula CnH2n02, high molecular weight alcohols and esters of these acids and alcohols.

The I. G. O. P., I. G. B., I. G. E. and. I. G. S. waxes are standard products of the I. G. Farbenindustrie Aktiengesellschaft Albino asphalt comprises an acid treated naphtha extract of a 300 F. melting point cracked residuum. It has a melting point of approximately 120'F.

In Table II is found a list of the physical characteristics of the accelerators appearing in Table I, and the class of chemical compositions to which sition under the influence of an electric current or electric field.

This invention also resides in the hereinbefore described electrodeposition dewax'ing aids and the employment thereof as aids to the process of electrodeposition of wax from wax-bearing oil.

The accelerators or promoters to electrodeposition have been found effective when used in;

conjunction with various oil solvents and diluents such as liquid propane, gaso1ine,'benzen'e, kero- 'sene,-carbon tetrachloride, and lubricating oil fractions.

An example of the practical application of the G. S. wax is added to the warm oil-propane solution in a small quantity ranging between 0.2% to 0.5% of the volume of the oil. The solution they are each believed to be related. containing the accelerator is self-chilled by re- Table II Electrodeposition 12 3 (c) o l p. M. P. F. Chemical composition amlemt No. No. (UbbeL) 13.8 113 219 Esters of montanic acid. 57. 8 148 177. 5 Esters oi montanic acid. 14.3 142 166 Esters oi montanic acid. 143. 0 170 181 Esters oi montanic acid. 64. 0 67 180 Contains montanic acid. 26.0 92 183 Contains montanic acid. 4. 0 71 184 Esters oi carnaubic acid. 20. 0 91 147 Contains melissic and cerotic aci A-Grade asphalt (dL 209-260 Petroleum pitch or residue. v Calcium stearate (e) Insoluble metallic soap. Formic acid (I) 47. 5 Organic acid-40% sq. sol. Stearine pitch Fatty acid. A i

(:1) Acid number (neutralization number) by the A. s. T. M. test D-l88-27'1. (b) Sap. No.-Saponiflcation number by the A. S. T. M. test D-94-28.

go) M. P.-Melting point, Ubbelohde.

d) 23-30% fixed carbon 75-05% sol. in 00h ductility 0. sp. gr. 1.09. (e) Insoluble in water. So]. in alcohol. Forms colloidal suspension (1) B. P. 100.8C. sp. gr. 1.218. t

Substances which have been found to produce the most pronounced promotion or acceleration of the rate of the electrodeposition of waxes from suspension in wax-bearing oils are-therefore believed to be of the following classes:

1 phenoxide and p-amlnophenol.

9. Petroleum residues, pitches or extracts thereof such as A-grade asphalt or albino asphalt.

This invention resides in a process for increasing the rate of electrodeposition of precipitated wax from wax-bearing oil wherein extraneous electrodeposition aids are added to the,wax-bear-' ing oil prior tochilling and the subsequently precipitated'wax resulting from chilling the mixture or solution removed from the oil by electro-depoin oil.

' duction of pressure and evaporation of propane to a temperature of 40 F.-at which temperature wax precipitates in the form of la fine suspension. The chilled mixture containing the precipitate is then passed between metallic plate electrodes which are spaced approximately inch apart, face to face, and which are charged to a unidirectional electropotential difference of 34,500 volts. The precipitated wax, which is in l most cases charged negatively, moves under the influence of the electric field between the electrodes and is deposited in a solid layer or coating 7 on the surface of the positively charged electrode.

The positive electrode plates, after receiving a coating of wax may be removed from the oil solution and the wax subsequently removed therefrom by suitable mechanical means. i

The quantity of wax deposited upon the electrode ina given period of time from the oil solution containing an accelerator is found to be increased to as much as 300% over that which is deposited upon the electrode under similar conditions' but without the presence of the added accelerator.

The oil-propane solution from which the wax has been electrically deposited is subsequently freed from the dissolved propane diluent by distillation to produce a dewaxed depropanized oil.

It is to be understood that the foregoing is 75 merely illustrative of one method of operation and that the invention is not limited thereby but may include other methods to accomplish the same within the scope of the invention.

I claim:

1. A process for dewaxing oil comprising adding an extraneous high molecular weight natural ester type wax to the wax-bearing oil, chilling thesolution to precipitate wax, subjecting the mixture to an electric field and separating wax from the oil.

2. A process for dewaxing oil comprising adding to the wax-bearing oil a high molecular weight wax material, chilling the solution to pre- 'cipitate wax, and removing the wax from the mixture, by electrodeposition, the added high molecular weight wax being chosen from the group consisting of esters of montanic, carnaubic, melissic, palmitic and cerotic acids.

3. A process for dewaxing oil comprising adding a high molecular weight wax material comprising an ester of montanic acid to the waxbearing oil, chilling the solution to precipitate wax, subjecting the mixture to an electric field and separating wax from the oil,

' 4. A process for dewaxing oil comprising adding Montan wax to the wax-bearing oil, chilling the solution to precipitate wax, subjecting the mixture to an electric field and separating wax from the 0111' 5. A process for dewaxing oil comprising adding a high molecular weight wax material comprising an ester of camaubic acid to the wax-bearing oil, chilling the solution to precipitate wax, subjecting the mixture to an electric field and separating wax from the oili 6. A process for dewaxing oil comprising adding carnauba wax to the wax-bearing oil,

chilling the solution to precipitate wax, subjectin'g the mixture to an electric field and sepa rating wax from the oil.

7. A process for dewaxing oil comprising adding a high molecular weight wax material comprising an ester of melissic acid to the wax-bearing oil. 7 

